1. Industrial Field of the Invention
The present invention relates to improvement of a fuel erroneous supply prevention shutter provided in a filler neck portion of a filler pipe in an automobile.
2. Prior Art
There is provided in a filler neck portion of a filler pipe a shutter for preventing inadequate supply of different fuel. When a fuel exclusive for a car is supplied by a supply nozzle having a particular nozzle shape, the shutter is opened to admit the fuel supplying nozzle into the filler pipe so as to supply fuel to a fuel tank. In case of the inadequate kind of fuel, however, the shutter serves to inhibit the supplying nozzle from being inserted through a nozzle restricting passage formed in the filler neck portion. Further, when a distal end portion of the supplying nozzle is forced against the shutter to open it and to supply the fuel from the supplying nozzle, an automatically shut-off mechanism provided on the supplying nozzle operates to close the nozzle valve of the supplying nozzle in response to the existence of the shutter.
As examples of a conventional shutter having such function, there are listed both a shutter of a leaf spring type as disclosed in U.S. Pat. No. 4,135,562 or 4,770,677, and a shutter actuated by a coil spring as disclosed in U.S. Pat. No. 4,955,950.
In the latter shutter employing the coil spring, the number of component parts is large so that assembling work becomes tedious. On the contrary, the former shutter of a leaf spring type has an advantage in that it can be constituted simply.
However, the structure of the conventional shutter of the leaf spring type, has a fault of durability in opening and closing action which is a function of the shutter. This is because it is difficult to design the leaf spring such that it maintains a certain biasing force to suitably close the passage and it can be used within an elastic range.
Basically, if the deformable portion of the shutter is sufficiently elongated, stress is distributed without concentration and the deformable portion can bend within the elastic range. However, the deformable portion having a sufficient length cannot be formed under restraint of the inner space, where the shutter is to be housed, depending on a diameter of the filler pipe.
From the viewpoint of character of the leaf spring, unless the leaf spring is used within the elastic range of the spring character, it loses its elasticity because of metal fatigue during repetition of opening and closing movement, so that the shutter will not be again restored to the closing state.
The present invention aims to provide a fuel erroneous supply prevention shutter of a leaf spring type whose durability in opening and closing action is improved.